Neural Tube DefectsFolic AcidFood, FortifiedVitamin B ComplexBreadFolic Acid DeficiencyFlourSpinal DysraphismVitamin B 12 DeficiencyNeural TubeVitamin B 12AnencephalyHomocysteineCerealsDietary SupplementsEncephaloceleAnemia, MacrocyticHomocystinePregnancyNutrition PolicyPrenatal CareNutritional RequirementsSpina Bifida OccultaPreconception CareNutritional StatusNeurulationNutrition SurveysInfant, NewbornSpina Bifida CysticaMeningomyeloceleErythrocytesUnited StatesTetrahydrofolatesHematinicsPrenatal DiagnosisPrevalenceCongenital AbnormalitiesVitaminsAbortion, TherapeuticMethylenetetrahydrofolate Reductase (NADPH2)alpha-FetoproteinsIrelandNeural CrestIncidenceFolate Receptors, GPI-AnchoredNervous SystemAir Pollution, RadioactiveMouth AbnormalitiesAmniocentesisEmbryo, MammalianPrenatal Nutritional Physiological PhenomenaHyperhomocysteinemiaAmniotic FluidFolic Acid AntagonistsFetal DeathAnemia, Iron-DeficiencyIron, DietaryGene Expression Regulation, DevelopmentalMicronutrientsCentral Nervous SystemCondimentsFolate Receptor 1Chick EmbryoDietTailZinebMethylenetetrahydrofolate Dehydrogenase (NADP)Paired Box Transcription FactorsPregnancy ComplicationsMice, Mutant StrainsVitamin B 6Embryonic and Fetal DevelopmentPregnancy in DiabeticsBody PatterningBiological AvailabilityNotochordGestational AgeIn Situ HybridizationThymidine MonophosphateEmbryonic DevelopmentCleft LipFetal DiseasesCase-Control StudiesIronMaternal Nutritional Physiological PhenomenaManebCleft PalateFormate-Tetrahydrofolate LigaseMaternal Exposure